1. Field of the Invention
The present invention relates to a display device.
2. Description of the Related Arts
For example, in an organic EL (electroluminescence) display device, by allowing an electric current to independently flow into organic EL elements provided to respective pixels, the organic EL elements are made to respectively emit light and the light emission brightness substantially corresponds to the current quantity.
When the light is emitted from the organic EL elements for a long time, there arises a drawback that the deterioration of the organic EL elements progresses and hence, the light emission brightness is lowered.
When an image is displayed on a display area which is a mass of the respective pixels, such a phenomenon leads a so-called fixed pattern in which the image exhibits the small display brightness and, when this fixed pattern is continued to be displayed for a long time, a so-called sticking is liable to easily occur.
Accordingly, there has been known a technique which obtains an average brightness of a display area by measuring a total quantity of electric current which flows in respective organic EL elements of an organic EL display device and controls voltages applied to the organic EL elements to lower an actual display brightness than a display brightness during a usual display when the average brightness is high.
This technique is based on a phenomenon that when the screen is bright as a whole as in the case of displaying an image which is substantially occupied with a white portion, the display quality is not largely influenced even when the display brightness of the whole screen is lowered, while when the screen is almost dark as in the case of displaying an image which is substantially occupied with a black portion, the display quality is influenced when the display brightness of the bright portion is lowered.
Such a technique is disclosed in Japanese Patent Laid-open 2003-330421.